(CNSNews.com) – A looming visit to Lebanon by Iranian President Mahmoud Ahmadinejad has raised concern in Israel and the United States, while stoking controversy inside Lebanon itself, where political and sectarian tensions are once again running high.

On his first visit to Lebanon since becoming president in 2005, Ahmadinejad plans next week to visit the border area in the south of the country, long a flashpoint in the ongoing conflict between Israel and the Iranian-backed Shi’ite terrorist group, Hezbollah.

Ahmadinejad also is due to meet with President Michel Suleiman, Prime Minister Saad Hariri and Hezbollah leader Hassan Nasrallah, according to the Iranian government.

Israel has expressed its objections to the Lebanese government, by way of the United Nations, and State Department spokesman Philip Crowley confirmed Tuesday that Secretary of State Hillary Clinton raised the matter with Suleiman when they met at the U.N. last month.

“Iran, through its association with groups like Hezbollah, is actively undermining Lebanon’s sovereignty,” Crowley said, but added that the visit was ultimately a decision for the Lebanese government to make.

Ahmadinejad has been invited by Suleiman, a former army commander who has long voiced sympathies with Hezbollah.

Two months ago Suleiman suggested that Lebanon would look to “friendly countries” to supply weapons for its army should the U.S. stop doing so. Some U.S. lawmakers had urged a shift in U.S. policy after Lebanese Armed Forces (LAF) opened fire on Israeli soldiers along the border.

The pan-Arab daily newspaper Asharq al-Awsat on Wednesday cited Iranian diplomatic sources as saying Ahmadinejad would be accompanied on the trip by a large business delegation and would offer Lebanon weaponry and help in oil exploration.

The planned two-day visit by the provocative Iranian also threatens to roil Lebanon’s fragile political setup.

While Suleiman defended it on Monday, saying it was Lebanon’s sovereign decision to decide which heads of state to receive, officials from Hariri’s mostly Sunni March 14 alliance on Wednesday voiced unease that a visit by Ahmadinejad to the south could be dangerous.

Tribunal troubles

Hezbollah, which many governments view as Iran’s proxy in Lebanon, is an armed militia whose continued existence violates U.N. Security Council resolutions.

It also operates as a political party, and is part of the Hariri-led “unity” government, with Hezbollah and its allies controlling 10 of the 30 cabinet seats.

The visit by the leader of its main sponsor comes amid heightened tensions surrounding the U.N.-mandated investigation into the 2005 assassination of Hariri’s father. Former prime minister Rafik Hariri was killed in a massive car bomb in Beirut which also claimed 22 other lives.

The Special Tribunal for Lebanon (STL), based in The Hague, is expected at some point to indict members of Hezbollah in the killing, while Syria – Hezbollah’s other major ally – has from the outset also been widely suspected of involvement.

Both Hezbollah and Syria have been trying to discredit the tribunal which they, along with Iran, accuse of bias and of being part of a “Zionist” plot.

In Hezbollah’s case, Nasrallah vowed not to cooperate with the STL and late last month turned down its requests to interview some Hezbollah members. Hezbollah also announced it would use its position in the government to try to block Lebanon’s funding for the STL. Lebanon is currently liable for 49 percent of the tribunal’s costs, with the rest coming from the international community.

Syria made its move at the weekend, issuing arrest warrants for 33 people – “judges, security officers, politicians, journalists and other Lebanese, Arab and foreign individuals” – whom it accused of giving false testimony to the STL in a bid to implicate Syria.

One of those named was Detlev Mehlis, a German judge who led an initial U.N. investigation into the Hariri assassination. That probe, a precursor to the STL, implicated top-level Syrian and Lebanese security officials.

The March 14 alliance leadership at a meeting Wednesday reiterated its support for the tribunal, and said the arrest warrants threatened to set back efforts to improve Lebanon-Syria relations.

Complicating the case is the position of Hariri himself. As the son of the slain man he has been a firm supporter of the tribunal. But he has also sought to improve ties with Damascus and in a stunning reversal last month told an Arab newspaper that he had been mistaken to blame Syria for his father’s murder.

The about-face sparked a furor in Lebanon, where some commentators seeking to explain his decision said he may have been motivated by a desire to prevent further Sunni-Shi’ite conflict.

U.N. Secretary-General Ban Ki-moon on Wednesday urged all parties in Lebanon and the region to stop trying to undermine the tribunal or to prejudge the outcome of its investigations.

“This tribunal is independent, with a clear mandate from the Security Council to uncover the truth and end impunity,” he said during a press conference in New York.

Asked about the funding issue, Ban said the Lebanese government had an obligation to meet its 49 percent of the costs.

His spokesman, Martin Nesirky, implied a day earlier that if the plug was pulled on Lebanese government funding for the STL, the Security Council would fill the gap.

Noting that the STL operates under a mandate from the Security Council, he said, “we would strive to ensure that it can go about its work.”

The U.S. Embassy in Beirut said Tuesday it would in the coming days update its travel warning for Lebanon, although it said the update was a “routine” matter. The current warning urges American citizens to “avoid all travel to Lebanon due to current safety and security concerns.”